Fishburne, an Emmy and Tony winner, will be introduced in the ninth episode of the upcoming 10th season, the network told the Associated Press on Monday. He'll play a forensics scientist with a secret.

Fishburne is a CSI newcomer in more ways than one. Asked if he's a fan, he told a teleconference Monday that he was embarrassed to admit he had never watched before he was approached by producers.

"But I am now," he said. He screened past episodes that were engaging and "kind of dark and moody, like the work I've been involved in," he said.

He was their top choice, said executive producers Carol Mendelsohn and Naren Shankar, with a deeply intelligent approach to his work that matches the drama's spirit.

This is the first ongoing series role for the in-demand film and stage actor since, improbably enough, he played Cowboy Curtis on Pee-wee's Playhouse in the late 1980s. He's not stepping away from movies with CSI, Fishburne said, but embarking on a "welcome change." Fishburne plays a college lecturer and former pathologist who is focused on why people commit acts of violence.

The air date for Petersen's final episode has yet to be determined but will be early next year. Petersen has been with the series since it debuted in fall 2000 and will remain a CSI executive producer, the network said.

Fishburne's character has a deep connection to his work: His genetic profile has been identified in serial killers, CBS programming chief Nina Tassler said before Fishburne's casting was announced but as rumors swirled.

Fishburne, 47, received an Oscar nomination for his portrayal of Ike Turner in 1993's What's Love Got to Do With It and a Tony in 1992 for Two Trains Running. He was a Tony nominee this year for the one-man show Thurgood, about Supreme Court Justice Thurgood Marshall.

The long-running CSI remains key for CBS: It finished last season as the network's top-rated series, ranking No. 9 among all shows with an average weekly audience of 17-million. Spinoffs CSI: Miami and CSI: New York ranked 16th and 28th, respectively.

Producers have been mum about upcoming plot points. But they said Petersen's character, Gil Grissom, will be reappraising his life after years of high-tech forensics investigations with the Las Vegas Police Department and after facing personal turmoil.